nvirtual-exterior

Arguments:
window-or-screen box

Returns the bounding box of all monitors in the system on newer
versions of Windows, when passed the screen. On Windows with multiple
monitors, the returned box will be the bounding rectangle for all
monitors when window-or-screen is the screen.
Otherwise this function returns the same box as nexterior.

window-or-screen should be either a window
or the screen. For a window this is the same as calling nexterior.